Minecraft – 110813 in Minecraft

Yes, food now only replenishes your hunger bar, and if the hunger bar is high enough, you will regenerate health at a fixed rate (~1/2 hp/5 sec at 90-100% sated). Conversely, and depending on difficulty, when you're starving you will either lose health until you hit 50% (easy), 5% (normal) or die (hard).

Various actions including walking, swimming, running, and stabbing things will increase your hunger (though notably not boating).

Food now stacks to 64, so it should be plenty easy to carry around enough for quite a while.

If you don't want to die while fighting hostile mobs, don't be so reckless; wear armor and/or take them out at range with a bow. As of 1.9 and 1.0 release, you can also use potions (Potion of Instant Health and Potion of Regeneration) to supplement your longevity. A Golden Apple also gives the same effect as the Potion of Regeneration, though owing to the extreme rarity probably not worth it.

The Minecraft day is 20 (real-life) minutes long, which translates into 24000 game ticks (there are 20 ticks per second).

Sunrise is implemented as the last part of the day-night cycle and is 90 seconds (1800) ticks) long (according to the wiki), starting at around game time 22200

when the sky will look like this (facing due east)

to game time 0 when the sky will look like this (also facing due east)

The easiest way to detect sunrise is to use the daylight sensor that has been introduced in the snapshots in combination with a comparator